Flask



FIG. 1 is a front elevational view of a flask showing my new design;

FIG. 2 is a side elevational view looking from the right of FIG. 1;

FIG. 3 is a rear elevational view;

FIG. 4 is a top plan view; and

FIG. 5 is a bottom plan view. 

The ornamental design for a flask, as shown and described. 